1. Field of the Invention
The present invention relates to a method for high-speed data transmission in wireless communication systems, particularly to a method for controlling transmission of high-speed data traffic in IPDLs.
2. Background of the Invention
Wideband Code Multiple Address (WCDMA) systems use a plurality of approaches to locate mobile stations. In one of those approaches, a mobile station measures time differences when a signal arrives from different base stations. The base station in the cell where the mobile station is located should be closed temporarily to decrease interference. This helps facilitate a mobile station to measure the time when the signal arrives from other base stations, avoid any interference of nearby service base stations to the mobile station, and enhance the receiving sensitivity of the signal from remote base stations. The time of closing downlink transmittion, i.e., IPDL, is usually half of a time slot, and an IPDL occurs usually every 100 ms. The mobile station measures the time when the signal arrives from other base stations through IPDL so that the mobile station can locate itself.
Idles in downlinks are implemented at the cost of system performance. During IPDLs, the base station closes the signal transmitting downlink; thus, all mobile stations in the coverage area of the base station cannot receive the signal in half of a time slot every 100 ms, which means all the mobile stations lose information in half of a time slot. For fault tolerant and low speed traffic (e.g., voice), such deep-attenuation-like transitory losses can be compensated with TTI error correction codes due to the long transmission time interval (TTI). However, for high-speed data traffic (e.g., 10 Mbps), the data loss in half time slot will reach 3333 bits. Furthermore, such data loss can't be compensated merely with error correction codes because TTIs for high-speed data traffic may be as short as a time slot. At the same time, packet switched data requires zero error data transmission, and data unable to be corrected will be retransmitted. Therefore IPDL will decrease the utilization coefficient of channels.